The invention relates to a device for monitoring the filling of a bag, comprising a resistor element to be attached to the outside surface of the bag said resistor element having an electric resistance changing by the shape change of the bag during filling thereof, to be connected to an alarm device responding to a predetermined resistance value of the resistor element.
A monitoring device of this kind is described in SE-B-466 381.
The prior art device comprises an electric resistor element the electric resistance of which changes by stretching of the element which is mounted over an extendable portion of the bag wall. The resistor element is stretched elastically manually and is then mounted to the outside surface of the bag. When it is then released it contracts forming a fold or a wrinkled or folded portion of the bag wall. As the bag is filled the fold or the wrinkled or folded portion will be smoothed down under elastic stretching of the resistor element and thus successive change of the resistance thereof. At a predetermined resistance value alarm is given by the alarm device. Said predetermined resistance value should be at such level that alarm is given when the bag is filled or nearly filled.
The resistor element of the prior art device can be stretched to a varying degree when being mounted to the bag, which means that the resistance value of the resistor element is not under complete control at mounting to the empty bag and thus it cannot be assured that said predetermined resistance value will be attained when the bag is filled. Moreover, not all bags are of such nature that the bag wall after mounting of the resistor element forms a fold or a wrinkled or folded portion under said element, which will be smoothed down under filling of the bag in order that the resistor element shall provide a reliable indication of the filling degree of the bag. Also the possible ageing or fatigue of the resistor element by repeated use has to be taken into account jeopardizing the intended purpose of the monitoring device.
The object of the invention is to provide a device for monitoring the filling of a bag, which provides a more reliable sensing of the filling degree of the bag because the mounting of the resistor element on the bag includes no manual step which may cause a non-desired variation in the initial resistance of the resistor element and thus uncertainty of the relation between the resistance value and the filling degree of the bag. It is also an object to provide a device of the kind referred to which can be used on bags of any existing type in order to provide reliable monitoring of the filling of the bag and which can easily be mounted to the bag and additionally is of a simple construction.
In order to achieve these and other objects which will be apparent from the description which follows the invention provides a device of the kind referred to having the characterizing features set forth in claim 1.
The device of the invention can be used on any drainage bag used in the medical care but is proposed in the first place for use on stomi bags in order to give an alarm when the stomi bag is full but not yet so full that there is a risk of the bag will come off the user""s body where it is attached by tape over the stoma, which would of course involve great discomfort for the user. However, the device can be used also in the industry for monitoring the collection of liquids of different kinds, for example the collection of condensate from dehumidifiers.